diff --git a/mozilla/modules/libpr0n/public/imgIRequest.idl b/mozilla/modules/libpr0n/public/imgIRequest.idl
index 55dab291668..5f0aa0aca01 100644
--- a/mozilla/modules/libpr0n/public/imgIRequest.idl
+++ b/mozilla/modules/libpr0n/public/imgIRequest.idl
@@ -25,6 +25,7 @@
 #include "nsIRequest.idl"
 
 interface imgIContainer;
+interface imgIDecoderObserver;
 interface nsIURI;
 
 /**
@@ -62,6 +63,8 @@ interface imgIRequest : nsIRequest
   readonly attribute unsigned long imageStatus;
 
   readonly attribute nsIURI URI;
+
+  readonly attribute imgIDecoderObserver decoderObserver;
 };
 
 %{C++
diff --git a/mozilla/modules/libpr0n/src/imgRequest.cpp b/mozilla/modules/libpr0n/src/imgRequest.cpp
index 8311b967f31..3afaaa7cccc 100644
--- a/mozilla/modules/libpr0n/src/imgRequest.cpp
+++ b/mozilla/modules/libpr0n/src/imgRequest.cpp
@@ -275,6 +275,12 @@ NS_IMETHODIMP imgRequest::GetURI(nsIURI **aURI)
   return NS_ERROR_FAILURE;
 }
 
+/* readonly attribute imgIDecoderObserver decoderObserver; */
+NS_IMETHODIMP imgRequest::GetDecoderObserver(imgIDecoderObserver **aDecoderObserver)
+{
+  return NS_ERROR_FAILURE;
+}
+
 
 /** imgIContainerObserver methods **/
 
diff --git a/mozilla/modules/libpr0n/src/imgRequestProxy.cpp b/mozilla/modules/libpr0n/src/imgRequestProxy.cpp
index 34fbe483a6f..3355ea27612 100644
--- a/mozilla/modules/libpr0n/src/imgRequestProxy.cpp
+++ b/mozilla/modules/libpr0n/src/imgRequestProxy.cpp
@@ -164,6 +164,15 @@ NS_IMETHODIMP imgRequestProxy::GetURI(nsIURI **aURI)
   return mOwner->GetURI(aURI);
 }
 
+/* readonly attribute imgIDecoderObserver decoderObserver; */
+NS_IMETHODIMP imgRequestProxy::GetDecoderObserver(imgIDecoderObserver **aDecoderObserver)
+{
+  *aDecoderObserver = mObserver;
+  NS_IF_ADDREF(*aDecoderObserver);
+  return NS_OK;
+}
+
+
 /** imgIContainerObserver methods **/
 
 /* [noscript] void frameChanged (in imgIContainer container, in nsISupports cx, in gfxIImageFrame newframe, in nsRect dirtyRect); */